Motor-driven compressor

ABSTRACT

A motor-driven compressor includes a housing made of a metal material, a compression portion, an electric motor, and a cover. The compression portion and the electric motor are accommodated in the housing, and the cover is attached to the housing. The cover is formed by a plastic portion and a shield made of a metal material that intercepts electromagnetic noise. A motor drive circuit for driving the electric motor is accommodated in an accommodation space defined by the housing and the cover. An elastic sealing member is located between the housing and the cover. The shield includes an extended portion that extends toward the housing and is arranged inside the sealing member. The extended portion is in contact with the housing.

BACKGROUND OF THE INVENTION

The present invention relates to a motor-driven compressor.

A motor-driven compressor includes a housing made of a metal material, which accommodates a compression portion that compresses refrigerant and an electric motor that drives the compression portion. A cover is attached to the housing. The cover defines an accommodation space in which a motor drive circuit for driving the electric motor is accommodated. A sealing member is located between the housing and the cover. The sealing member prevents wastes or water from entering the accommodation space through an interface between the housing and the cover.

When the cover is made of a metal material, the weight of the motor-driven compressor itself becomes heavy. In this regard, a cover made of plastic has been proposed to reduce the weight of the cover to reduce the weight of the motor-driven compressor itself. When a cover made of plastic is used, however, noise from the outside of the motor-driven compressor is likely to enter the motor drive circuit through the cover. Also, the noise from the motor drive circuit is likely to leak outside through the cover.

Accordingly, in the compressor disclosed in Japanese Laid-Open Patent Publication No. 2002-155862, a body of an inverter case (cover) is made of plastic by insert molding, and metal plating is performed on the inner side thereof. Since the metal plating is performed on the inner side of the body of the inverter case, the noise from the outside is intercepted by the metal plating so that the noise is restricted from entering the accommodation space through the plastic body. Further, since the noise from the motor drive circuit is intercepted by the metal plating, outside leakage of the noise through the body made of plastic is reduced.

In the compressor disclosed in the above publication, however, even if the inverter case (cover) with the body made of plastic in which the metal plating is performed on the inner side of the body is adopted, noise from the outside is likely to enter the accommodation space through the sealing member to flow through the motor drive circuit. Also, the noise from the motor drive circuit is likely to leak outside through the sealing member.

Heat is generated from the motor drive circuit, and the heat generated from the motor drive circuit is transferred to the cover. If the cover is made of plastic as in the compressor as disclosed in the above publication, the cover is less likely to dissipate heat compared with a cover made of a metal material. Further, in particular, since the sealing member is located between the cover and the housing, the heat transferred from the motor drive circuit to the cover is less likely to be dissipated to the housing. As a result, cooling performance of the motor drive circuit accommodated in the accommodation space is reduced.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a motor-driven compressor that reduces noise leakage though a sealing member and has an excellent cooling performance for a motor drive circuit.

To achieve the foregoing object and in accordance with one aspect of the present invention, a motor-driven compressor includes a housing made of a metal material; a compression portion and an electric motor accommodated in the housing; a cover attached to the housing; a motor drive circuit accommodated in an accommodation space defined by the housing and the cover; and an elastic sealing member located between the housing and the cover. The cover is configured by a plastic portion and a shield made of a metal material that intercepts electromagnetic noise. The motor drive circuit drives the electric motor. The shield includes an extended portion that extends toward the housing and is arranged inside the sealing member. The extended portion is in contact with the housing.

Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1A is a cross-sectional view, with a part cut away, showing a motor-driven compressor according to one embodiment;

FIG. 1B is a partially enlarged cross-sectional view showing the cover and its surrounding of the motor-driven compressor of FIG. 1A;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1B; and

FIG. 3 is a partially enlarged cross-sectional view showing a cover and its surrounding according to another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a motor-driven compressor according to one embodiment will be described with reference to FIGS. 1A, 1B, and 2.

As shown in FIG. 1A, a motor-driven compressor 10 has a housing H. The housing H includes a discharge housing member 11 made of aluminum (made of a metal material) and a suction housing member 12 made of aluminum (made of a metal material) joined to the discharge housing member 11. The discharge housing member 11 is shaped as a cylinder with a closed upper portion. The suction housing member 12 is shaped as a cylinder with a closed bottom portion. A suction port (not shown) is formed in a peripheral wall of the suction housing member 12 and the suction port is connected to an external refrigerant circuit (not shown). A discharge port 14 is formed in the discharge housing member 11, and the discharge port 14 is connected to the external refrigerant circuit. The suction housing member 12 accommodates a compression portion 15 for compressing rerigerant and an electric motor 16 for driving the compression portion 15. Although not particularly illustrated in the present embodiment, the compression portion 15 includes a fixed scroll, which is fixed to the suction housing member 12, and an orbiting scroll, which is arranged to face the fixed scroll.

A stator 17 is fixed to the inner circumferential surface of the suction housing member 12. The stator 17 includes a stator core 17 a fixed to the inner circumferential surface of the suction housing member 12, and a coil 17 b wound about each of teeth (not shown) of the stator core 17 a. A rotary shaft 19 is rotationally supported in the suction housing member 12 in a state in which the rotary shaft 19 is inserted through the stator 17. The rotary shaft 19 is secured to a rotor 18.

As shown in FIG. 1B, an annular extension 12 f is formed in a bottom wall 12 a of the suction housing member 12. The extension 12 f extends outward (rightward as viewed in FIG. 1B) from the whole peripheral circumference of the bottom wall 12 a in a direction in which the axial center L of the rotary shaft 19 extends (axial direction). A cylindrical cover 41 with a closed end is attached to an opening end of the extension 12 f. Further, accommodation space 41 a is defined by the bottom wall 12 a, the extension 12 f, and the cover 41. The accommodation space 41 a accommodates a motor drive circuit 40, which drives the electric motor 16. The motor drive circuit 40 is attached to the bottom wall 12 a in the accommodation space 41 a. Accordingly, in the present embodiment, the compression portion 15, the electric motor 16, and the motor drive circuit 40 are arranged in this order in the axial direction of the rotary shaft 19.

The cover 41 is formed by a plastic portion 42 and a shield 43 made of aluminum (made of a metal material). The plastic portion 42 is shaped as a cylinder with a closed end and configures the body of the cover 41. The cover 41 is molded by a plastic material using the shield 43 as a metal core. Accordingly, the cover 41 is mainly formed from a plastic material. The shield 43 is arranged inside the plastic portion 42.

The plastic portion 42 includes an annular outer cylindrical portion 42 a, an outer lid portion 42 b, and an annular outer connector portion 42 c. The outer cylindrical portion 42 a extends in the axial direction of the rotary shaft 19. The outer lid portion 42 b is continuous with the outer cylindrical portion 42 a and extends in a direction perpendicular to a direction in which the outer cylindrical portion 42 a extends. The outer connector portion 42 c is continuous with the outer lid portion 42 b and extends in the axial direction of the rotary shaft 19.

The shield 43 includes an annular inner cylindrical portion 43 a, an inner lid portion 43 b, and an annular inner connector portion 43 c. The inner cylindrical portion 43 a extends in the axial direction of the rotary shaft 19. The inner lid portion 43 b is continuous with the inner cylindrical portion 43 a and extends in a direction perpendicular to a direction in which the inner cylindrical portion 43 a extends. The inner connector portion 43 c is continuous with the inner lid portion 43 b and extends in the axial direction of the rotary shaft 19. The inner cylindrical portion 43 a extends along an inner peripheral surface of the outer cylindrical portion 42 a of the plastic portion 42. The inner lid portion 43 b extends along an inner bottom surface of the outer lid portion 42 b of the plastic portion 42. The inner connector portion 43 c extends along an inner peripheral surface of the outer connector portion 42 c of the plastic portion 42. Accordingly, the shield 43 extends over the whole inner surface of the plastic portion 42, and intercepts noise (electromagnetic noise) through the plastic portion 42.

Inside the inner connector portion 43 c, a holding portion 45 made of a plastic material is integrally formed with the inner connector portion 43 c. A metal terminal 46 that is electrically connected to an external power supply (not shown) is held by the holding portion 45. The metal terminal 46 is electrically connected to the motor drive circuit 40.

A sealing member 51 made of an elastic rubber material is located between the opening end of the extension 12 f and the opening end of the outer cylindrical portion 42 a. The sealing member 51 is annular. Further, the inner cylindrical portion 43 a of the shield 43 extends toward the bottom wall 12 a (suction housing member 12) and is arranged inside the sealing member 51. Accordingly, in the present embodiment, the inner cylindrical portion 43 a corresponds to an extended portion arranged inside the sealing member 51, and the extended portion is provided in the shield 43. A tip end 431 a of the inner cylindrical portion 43 a protrudes further toward the bottom wall 12 a than an end surface 511 of the sealing member 51 facing the extension 12 f does. A portion in the vicinity of the tip end 431 a in an outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts an inner peripheral surface of the extension 12 f.

As shown in FIG. 2, the inner cylindrical portion 43 a is formed such that it contacts a whole inner peripheral surface 51 a of the sealing member 51. The outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts the inner peripheral surface 51 a of the sealing member 51. The sealing member 51 is installed on a peripheral portion of the inner cylindrical portion 43 a by being elastically deformed radially outward. The outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts the inner peripheral surface 51 a of the sealing member 51 so that the sealing member 51 is arranged to be in close contact with and along the outer peripheral surface 432 a of the inner cylindrical portion 43 a, and the sealing member 51 is maintained to be shaped to conform to a peripheral edge of the accommodation space 41 a. The inner diameter of the sealing member 51 prior to the elastic deformation is smaller than the outer diameter of the inner cylindrical portion 43 a.

Next, an operation of the present embodiment will be described.

The tip end 431 a of the inner cylindrical portion 43 a protrudes further toward the bottom wall 12 a than the end surface 511 of the sealing member 51 facing the extension 12 f does. Accordingly, noise from the outside through the sealing member 51 is intercepted by the inner cylindrical portion 43 a and noise from the motor drive circuit 40 toward the sealing member 51 is intercepted by the inner cylindrical portion 43 a as well. Accordingly, noise leakage through the sealing member 51 is reduced. Further, the portion in the vicinity of the tip end 431 a in the outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts the inner peripheral surface of the extension 12 f. Thereby, heat transferred from the motor drive circuit 40 to the shield 43 is dissipated to the housing H through the inner cylindrical portion 43 a.

The above described embodiment has the following advantages.

(1) The inner cylindrical portion 43 a of the shield 43 extends toward the bottom wall 12 a to be arranged inside the sealing member 51. Thereby, in comparison to a case in which the inner cylindrical portion 43 a is not arranged inside the sealing member 51, the noise from the outside through the sealing member 51 is easily intercepted by the inner cylindrical portion 43 a and the noise from the motor drive circuit 40 toward the sealing member 51 is easily intercepted by the inner cylindrical portion 43 a as well. Accordingly, the noise leakage through the sealing member 51 is reduced. Further, the portion in the vicinity of the tip end 431 a in the outer peripheral surface 432 a of the inner cylindrical portion 43 a is in contact with the inner peripheral surface of the extension 12 f. Accordingly, the heat transferred from the motor drive circuit 40 to the shield 43 is dissipated to the housing H through the inner cylindrical portion 43 a. This improves the cooling performance of the motor drive circuit 40 accommodated in the accommodation space 41 a.

(2) The inner cylindrical portion 43 a is provided over the whole inner peripheral surface 51 a of the sealing member 51. Thereby, in comparison to a case in which the inner cylindrical portion 43 a is provided at a part of the inner peripheral surface 51 a of the sealing member 51, noise leakage through the sealing member 51 is easily reduced and the heat transferred from the motor drive circuit 40 to the shield 43 is easily dissipated to the housing H through the inner cylindrical portion 43 a.

(3) The shield 43 has the inner cylindrical portion 43 a, which corresponds to the extended portion. Thereby, in addition to reduction of the noise leakage through the plastic portion 42, the noise leakage via the sealing member 51 is also reduced. Thus, it is simpler to provide the extended portion in the shield 43 than in the housing H.

(4) The outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts the inner peripheral surface 51 a of the sealing member 51. Accordingly, the outer peripheral surface 432 a of the inner cylindrical portion 43 a contacts the inner peripheral surface 51 a of the sealing member 51 so that the sealing member 51 is arranged to be in close contact with and along the outer peripheral surface 432 a of the inner cylindrical portion 43 a and the sealing member 51 is maintained to be shaped to conform to the peripheral edge of the accommodation space 41 a. Therefore, a sufficient seal between the opening end of the extension 12 f and the opening end of the outer cylindrical portion 42 a is easily ensured.

(5) According to the present embodiment, the heat transferred to the shield 43 is dissipated to the housing H through the inner cylindrical portion 43 a. Accordingly, electronic parts as heating elements configuring the motor drive circuit 40 are arranged in the vicinity of the cover 41 in the accommodation space 41 a. Therefore, flexibility of a layout in the electronic parts is improved.

(6) The inner cylindrical portion 43 a corresponding to the extended portion is arranged inside the sealing member 51. Since the extended portion is not arranged outside the sealing member 51, the shape on the outer peripheral side of the housing H and the shape on the outer peripheral side of the cover 41 are not complicated in the motor-driven compressor 10.

The above-mentioned embodiments may be modified as follows.

As shown in FIG. 3, a portion in the vicinity of the tip end 431 a of the inner cylindrical portion 43 a may have a spring property. A flexural portion 61 and a curved portion 62 are formed in a portion in the vicinity of the tip end 431 a of the inner cylindrical portion 43 a. The flexural portion 61 is flexed inward in the inner cylindrical portion 43 a. The curved portion 62 is a portion closer to the tip end 431 a of the inner cylindrical portion 43 a than the flexural portion 61, and is arcuately curved to bulges outward of the inner cylindrical portion 43 a. When the outer side of the curved portion 62 contacts the inner peripheral surface of the extension 12 f, the portion in the vicinity of the tip end 431 a of the inner cylindrical portion 43 a curves inward of the inner cylindrical portion 43 a at the flexural portion 61 as a flexural point. Accordingly, when attaching the cover 41 to the suction housing member 12, the portion in the vicinity of the tip end 431 a of the inner cylindrical portion 43 a curves to compensate for dimensional tolerance of the suction housing member 12 and the cover 41. This allows the inner cylindrical portion 43 a to readily contact the extension 12 f. Also, the cover 41 is easily attached to the suction housing member 12.

For example, a cylindrical member corresponding to the extended portion may be provided separate from the cover 41. For example, a cylindrical member may be attached to the inner cylindrical portion 43 a so that the cylindrical member corresponding to the extended portion may be provided on the cover 41.

The tip end 431 a of the inner cylindrical portion 43 a in a direction in which the tip end 431 a extends may protrude to the same position as the end surface 511 of the sealing member 51, which faces the extension 12 f. That is, the inner cylindrical portion 43 a may extend to a position at which the inner cylindrical portion 43 a covers at least the inner peripheral surface 51 a of the sealing member 51.

The inner cylindrical portion 43 a may be formed on a part of the inner peripheral surface 51 a of the sealing member 51. In this case, the inner cylindrical portion 43 a may be formed on any part that is susceptible to the noise in the inner peripheral surface 51 a of the sealing member 51.

The inner cylindrical portion 43 a need not contact the inner peripheral surface 51 a of the sealing member 51.

The motor drive circuit 40 may be attached to the cover 41 in the accommodation space 41 a.

The cover 41 may be attached to the outer peripheral surface of the suction housing member 12, for example.

Although the cover 41 is molded by the plastic material using the shield 43 as a metal core in the above illustrated embodiments, the cover 41 is not limited to this. The cover 41 may be formed by other methods. For example, an engaging projection may be provided on the plastic portion 42, and an engaging hole with which the engaging projection engages may be provided in the shield 43. The cover 41 may be formed by assembing the plastic portion 42 and the shield 43 together through engagement between the engaging projection and the engaging hole.

The shield 43 may be formed of a conductive material such as iron and copper.

Although the compression portion 15, the electric motor 16, and the motor drive circuit 40 are arranged in this order in the axial direction of the rotary shaft 19 in the above illustrated embodiments, the order of the arrangement is not limited to this. For example, the motor drive circuit, the compression portion, and the electric motor may be arranged in this order in the axial direction of the rotary shaft 19.

The compression portion 15 may be of a piston type or of a vane type, for example.

Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims. 

1. A motor-driven compressor, comprising: a housing made of a metal material; a compression portion and an electric motor accommodated in the housing; a cover attached to the housing and configured by a plastic portion and a shield made of a metal material that intercepts electromagnetic noise; a motor drive circuit accommodated in an accommodation space defined by the housing and the cover, wherein the motor drive circuit drives the electric motor; and an elastic sealing member located between the housing and the cover, wherein the shield includes an extended portion that extends toward the housing and is arranged inside the sealing member, and the extended portion is in contact with the housing.
 2. The motor-driven compressor according to claim 1, wherein the extended portion has a spring property.
 3. The motor-driven compressor according to claim 1, wherein the extended portion contacts a whole inner peripheral surface of the sealing member.
 4. The motor-driven compressor according to claim 1, further comprising: a rotor accommodated in the housing, the rotor configuring the electric motor; and a rotary shaft accommodated in the housing, the rotary shaft rotating integrally with the rotor, wherein the compression portion, the electric motor, and the motor drive circuit are arranged in this order in an axial direction of the rotary shaft.
 5. The motor-driven compressor according to claim 1, wherein the shield extends over a whole inner surface of the plastic portion.
 6. The motor-driven compressor according to claim 1, wherein the housing includes an annular extension contacting the sealing member, and wherein the extended portion is annular and has a tip end contacting the extension. 